In recent years, various types of treatments and examinations in the medical field have been performed using an elongated and hollow tubular-shaped medical instrument called a catheter. In such treatment methods, the following procedures in which a medical catheter is utilized using the elongated shape thereof have been performed. The treatment methods include a treatment method of directly administering an agent into an affected area using a catheter; a treatment method of extending and opening a narrowed section in the lumen in a living body using a catheter in which a balloon expanded by pressure is attached to a distal end thereof; a treatment method of scraping and opening the affected area using a catheter in which a cutter is attached to a distal portion thereof; and a treatment method of closing arterial aneurysm or bleeding sites, or a feeding vessel with a filling material using a catheter. The treatment methods further include a treatment method of embedding and placing a tubular-shaped stent which has a mesh-shaped side surface into the lumen in a living body using a catheter to maintain an open state of the narrowed section in the lumen in the living body. In addition, aspirating a thrombus that blocks a blood vessel is also included in the treatment methods.
When performing treatment, inspection, and the like using a catheter, in general, an introducer sheath is introduced into a puncture site formed in an arm or a leg using a catheter introducer, and a catheter or the like is percutaneously inserted into a lesion area in the blood vessel or the like through a lumen of the introducer sheath.
The introducer sheath is formed from a sheath tube which is a tubular member provided with a hollow portion through which an elongated body such as a catheter is freely inserted. An example is disclosed in Japanese Application Publication No. 08-131552. The introducer sheath is provided with a distal portion which becomes a distal side when introducing the introducer sheath into a puncture site; and a main body portion positioned at a proximal side of the distal